powers of two, recursion.
 

int ans, guess, random, type, counter, num, i;

char option[20], numb[10], input[5];





int power(int num)

{

    ans=2;

    if(num==0)

    {

        return(1);

    }    

    if(num<0)

    {

        printf("incorrect input, please input a positive integer:");

        return(0);

    }    

    

    else

        for(i=1; i!=num; i++)

            {

                    return(ans=ans*2);

            }    

    return(0);

} 



int main()

{

/*before this there is all the switch case stuff*/

case 1 : 

             /*powers of 2 calculator*/

printf("please enter a positive integer:\n");

fgets(numb, sizeof(numb), stdin);

sscanf(numb, "%d",&num);

printf("the answer is:%d\n",power(num));

break;



ok so the origional was:

case 1 : 

                                /*powers of 2 calculator*/

                        printf("please enter a positive integer:\n");

            fgets(numb, sizeof(numb), stdin);

            sscanf(numb, "%d", &num);

            ans=2;

            if(num<0)

            printf("incorrect input, please input a positive integer:");

            if(num==0)

            printf("the answer is 1\n");

            for(i=1; i!=num; i++)

            ans=ans*2;

            printf("The answer is %d\n", ans);

                        break;

and i had to take that and turn it into a recursive function. IDK what recursion is other than "it calls itself" or something... anyway im lost on this.
please help!

Re: powers of two, recursion.
 

here is the recursive code for calculating power of 2;
int power(int num)
{
if(num==0)
return 1;
if(num==1)
return 2;
return 2*power(num-1);
}

well after including this function in ur prog, u dont need to check whether the input value is 0 or 1. but check for -ve entry..

here is ur modified switch statements ...
case 1 :
/*powers of 2 calculator*/
printf("please enter a positive integer:\n");
fgets(numb, sizeof(numb), stdin);
sscanf(numb, "%d", &num);
//ans=2;
if(num<0)
printf("incorrect input, please input a positive integer:");
else{
ans=power(num);
printf("The answer is %d\n", ans);}
break;